Children and adults with significant communication challenges may rely on augmentative and alternative communication systems to communicate. Electronic communication devices that produce synthesized/digitized speech offer significant advantages to interaction, but only if the speech is sufficiently intelligible to the user and his or her communication partners. One way to improve the intelligibility of speech output, which is typically lower than natural speech, is by training the listener to better recognize and understand the output. The present application will address the question of whether a practice program will significantly improve the intelligibility of speech output for young children. The first aim of the application is to compare the effects of using words, sentences, and narratives as practice materials in increasing the intelligibility of synthesized speech for four-year-old listeners. A Two Factor Mixed design will be used to investigate the effects of these different practice materials. Children will be assigned to one of three conditions (word, sentence, or narrative-level practice), and will participate in four 20-minute practice sessions. The independent variables will be the practice materials (words, sentences, and narratives) and session (sessions 1, 2, 3, and 4). The dependent measures will include intelligibility of single words (percent of words correctly repeated), and intelligibility of sentences (percent of words in the sentence correctly repeated in isolated sentences and sentences within narratives). The second aim is to compare the effectiveness of two practice programs that differ in amount of listener engagement with the materials in increasing the intelligibility and comprehension of digitized and synthesized speech for four-year-old listeners. The second experiment will use a Three Factor Mixed design, using speech type (synthesized and digitized speech), the practice program (low engagement and high engagement), and session (sessions 1, 2, 3, and 4) as independent variables. The dependent measures will include intelligibility of single words (percent of words correctly repeated) and comprehension of commands (percent of single-step commands correctly executed). [unreadable] [unreadable]